Chapter 2
Input and Output Devices
Code Subject: 9713
Input and Output Devices
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Keyboards
Numeric Keyboards
Mice (Mouse)
Touchpad
Trackballs
Remote Controls
Joysticks
Touch Screens
Magnetic stripe readers
Sensors
Graphic tablets
Light Pens
3D Inkjet Printers
Dot Matrix
Plotters
MIDI instruments
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Smart card readers
Chip and PIN readers
Scanners
Barcode readers
OMR
OCR
MICR
Digital Cameras
Webcams
Microphones
CRT
TFT
Laser Printers
Inkjet Printers
Speakers
Projectors
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Input Devices
 Input devices are used to give data into the computer
system
 Input devices probably are ranged (wired or not)
 Input devices help people to control and use the
computer system, most of the times
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Input Devices
 Keyboard
◦ Most common input device
◦ input text, numbers, commands, password
◦ Concept keyboards (Shaped)
◦ Overlay Keyboards
◦ Advantages
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Accurate enter data
Quick entry of text
Robust
Help people with disabilities
◦ Disadvantages
 Difficult for people with disabilities
 Not quick compare with barcode, etc
 Take more space
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Input Devices (Cont.)
 Numeric Keypads
 Enter numbers
 Specific Scenarios such as ATM, PIN, Telephones, EPOS
terminals etc
 Advantages
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Small
Many devices in one machine
Easy to enter numbers
 Disadvantages
 Difficult to enter text
 Can be too small sometimes
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Input Devices (Cont.)
 Mice (Mouse)
◦ Pointing device
◦ Move pointer
◦ Buttons with different functions
◦ Scroll button
◦ Can be optical
◦ Can have one ball under the plastic case
◦ Advantages
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Faster to choice options
Fast navigation
Smaller then keyboards
◦ Disadvantages
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Difficult to use for people with disabilities
Easy to damage
Difficult to enter data like text numbers
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Input Devices (Cont.)
 Touchpad
 Used in laptop computers with fingers
 Same operation as mouse
 Advantages
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Same as mouse
Do not have to be plugged in
 Disadvantages
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Difficult control compare to mouse
Same as mouse
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Input Devices (Cont.)
 Tracker balls
◦ Ball on the top of it
◦ Same functionality with mouse and touchpad
◦ Control Pointer
◦ Control Room Environment
◦ Use for RSI
◦ Advantages
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People with limitations
Accurately
Desk space
◦ Disadvantages
 Expensive
 Need Training
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Input Devices (Cont.)
 Video digitizers
 Input video to computer
 Convert analogue to digital signals
 Fitted into your computer
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Input Devices (Cont.)
 Remote Controls
 Control devices remotely
 Buttons help to choose diff options
 Wireless communication
 Used for home entertainment devices
 Advantages
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Can be in distance from the devices
Help people with disabilities
 Disadvantages
 People with RSI diff to use it
 Stop working with obstacle in front of it
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Input Devices (Cont.)
 Joysticks
◦ Similar functions with mouse and trackball
◦ Stick, move around to select options
◦ Move objects around the screen
◦ Used for games
◦ Airline pilots
◦ Advantage
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Control objects in three dimensions
Faster to choose options
◦ Disadvantage
 Diff to enter data
 Diff to control pointer than other windows icons, etc
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Input Devices (Cont.)
 Touch screens
◦ Can be input and output
◦ Use fingers or stylus
◦ Icons on the screen represent buttons
◦ ATM
◦ EPOS
◦ Tourist information kiosk
◦ PDA
◦ Interactive whiteboards
◦ Advantage
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Faster entry of options
Easier for people with disabilities
Less possibilities to choose wrong options
◦ Disadvantage
 Diff to enter text
 Diff for people with RSI
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Input Devices (Cont.)
 Magnetic strip readers
◦ Read information form plastic cards
◦ 3 tracks are used to store information
◦ Banking for example use second track
◦ ATM
◦ EFTPOS
◦ In security
◦ Advantage
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Faster entry of data
More accurate
More secure
Prevents entry of restricted areas
◦ Disadvantage
 If damaged, lost speed
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Input Devices (Cont.)
 Smart card readers or chip card
◦ Information is stored on a chip
◦ Used to store a PIN number
◦ Payment method
◦ Satellite broadcasters
◦ SIM cards
◦ Passport
◦ Advantage
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Immediate update, no fraud
Less damage thought regular use
More secure
Enter in restricted areas without card
◦ Disadvantage
 Hackers can stole information
 if the card lost the owner loses a proportion, if not all the money value of the card
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Input Devices (Cont.)
 Chip and PIN readers
◦ Type of smart cards
◦ EFTPOS terminals
◦ Has slot for inserting the chip card and keypad for entering the PIN
(personal identification number)
◦ Some of them has slot for magnetic strip cards
◦ Chip has information but also the PIN
◦ The card can not be used unless the people know the PIN
◦ Use for payment methods
◦ Advantages
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Secure transactions
Save time compare using cash and cheques
More robust
◦ Disadvantages
◦ No PIN no transactions
◦ Very careful to protect their PIN
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Input Devices (Cont.)
 Scanners
◦ Enter hard copy images
◦ Flat pad, place the document in front of the glass
◦ Light source move underneath
◦ Scanner can also used as OCR
◦ Barcode readers are used to reader codes
◦ Use to scan old records
◦ Scan images for editing
◦ Used in faxes
◦ Advantages
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Allow images to be stored
Save time using as OCR
Using as barcode, save time and more accurate
◦ Disadvantage
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Reproduction is limited
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Input Devices (Cont.)
 Barcode readers
◦ Read information in the form of bar code
◦ Goods are marked with codes
◦ Uses
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Supermarkets and shops
Automatic stock control
Libraries
Identify items from the database
◦ Advantages
 Faster
 Accurate
 Improve safety
 Trusted
 Easy update (only central database)
 No individually changes
◦ Disadvantages
 Expensive
 Barcodes can be swapped
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Input Devices (Cont.)
 OMR – Optical mark recognition
 Read marks made by pen or pencil
 Uses
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Read multiple choice questions
 Advantages
 Fast
 More accurate
 OMR more accurate than OCR
 Disadvantages
 Forms need to be carefully designed
 Problems, if the forms haven’t been fill correctly
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Input Devices (Cont.)
 OCR – optical character recognition
◦ Scan text and convert it into computer readable form
◦ Uses
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Processing of passport and identity cards
Used when scanning documents for further manipulation
◦ Advantages
 Faster data entry
 Reduce number of errors
◦ Disadvantages
 Difficult to read hand writing
 Not very accurate technique
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Input Devices (Cont.)
 Digital Cameras
 Used like traditional camera
 Photographs can be deleted if they are not good
 Also can be retaken
 Camera can be connected directly to the computer
 Also can use photo editing packages to manipulate
photos
 Most cameras has capacity to store many photographs
 Digital cameras can also take short videos
 Used by personal photographers
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Input Devices (Cont.)
 Digital Cameras (cont.)
 Advantages
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Better quality photos than traditional camera
Quicker to upload images than scan them in
Quicker and safer than to have a film
Memory card can hold more images
 Disadvantages
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More expensive
Batteries need changing more often than with traditional
cameras
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Input Devices (Cont.)
 Microphones
◦ Connected directly to the computer
◦ Input sounds
◦ Sounds converted from electrical analogue signal into digital
signal in order to be stored and manipulated
◦ This is done by computer sound cards
◦ Used to detect text for use with voice recognition software
◦ Voice cover in slide shows or web pages
◦ Advantages
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Changes to the sound can be done in real time
Quicker to input text by speaking rather than typing
◦ Disadvantages
 Computer can use the input speech for one purpose only at that time
 Not accurate as using keyboard
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Input Devices (Cont.)
 Sensors
◦ Sensor is used to input data about physical changes in an environment
◦ Convert analogue data into digital data
◦ Sensors are used to control and monitoring applications
◦ Uses
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Temperature sensor
Pressure sensor
Light sensor
Sound sensor
Humidity sensor
◦ Advantages
 More accurate
 Readings are continues
 Necessary action will be initiated immediately
 Automatic systems
◦ Disadvantages
 Faulty sensors can give wrong results
 Power cut, reading can not be taken
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Input Devices (Cont.)
 Web cameras
◦ Smaller than video camera
◦ Connected directly to the computer though usb
◦ Laptops have webcams built into the top of the monitor
◦ Uses
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Chatting online (MSN)
Enable video conferencing
◦ Advantages
 Allow people to keep in contact without need to travel
 Activated as required
◦ Disadvantages
 They need to be connected to the computer
 Limited features and poor quality
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Input Devices (Cont.)
 MIDI
◦ Musical instrument digital interface
◦ The interface converts the signals into digital
◦ Uses
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Performance directly recorded to the computer and stored as
MIDI file
MIDI files can supplement other MIDI files
◦ Advantages
 Errors can be removed
 Files can be manipulated
◦ Disadvantages
 Music is not spontaneous
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Input Devices (Cont.)
 Graphics tablets
◦ Hand drawn images
◦ Resulting image appear on the computer monitors for further
use
◦ Uses
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Computer graphics
Computer aided design
Chinese and Japanese characters
◦ Advantages
 Accurate drawing
 Drawings are input rather than letters as happens with scanners
◦ Disadvantages
 More expensive
 Difficult to use for choosing menu selections
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Input Devices (Cont.)
 Light pens
◦ Contain sensors that send signal to computer whenever light change are
detected.
◦ Only work in CRT monitors
◦ Images built up row by row and refreshed 50 time every second
◦ Uses
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Selecting objects on CRT screens
Drawing on screen (CRT)
◦ Advantages
 More accurate than touch screens
 Small
 Easy to use
◦ Disadvantages
 Lag
 Only work on CRT
 Not accurate when drawing
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Output Devices
 CRT Monitors
◦ Use an electron gun to fire against phosphor screen
◦ Dots is colored red, blue, green
◦ Not expensive
◦ Uses
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Primary output device of a computer
Light pens
◦ Advantages
 Higher quality images than TFT
 Better angle of viewing
 Light pens in CAD
◦ Disadvantages
 Very hot
 Too heavy
 Need more power
 Eye side problems
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Output Devices (Cont.)
 TFT Monitors
◦ Nowadays are the main output device
◦ Thousand of pixels
◦ Each pixel has three transistors, colored red, blue, green
◦ Uses
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Used on laptops
◦ Advantages
 Lightweight
 Less glare and radiation
 Less power
◦ Disadvantages
 Problems when viewed slightly from the side
 Less definition than CRT
 Not used with light pens
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Output Devices (Cont.)
 Laser printer
◦ Very high quality hard copy
◦ Large buffer memories
◦ All pages are stored and then printed out
◦ Uses
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Noise level need to keep low, like in office
Very high quality hard copy
◦ Advantages
 Fast in large amount of printing pages
 Handle very large printing jobs
 Lower cost in toner cartridge
◦ Disadvantages
 Expensive
 Only fast in several copies
 Four cartridges
 Health issue
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Output Devices (Cont.)
 Inkjet printer
◦ Good quality hard copies
◦ Better than dot matrix
◦ Printing is done a bit at time
◦ Uses
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High quality for small job
Low output volumes
Very good to produce photo quality printouts
◦ Advantages
 Cheaper to buy
 High quality
 Lightweight and need small space
 No healthy issues
◦ Disadvantages
 Slow output for large amount of pages
 Cartridge run out quickly
 Printing can smudge
 Expensive to run if they are used a lot
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Output Devices (Cont.)
 3D inkjet printers
◦ Produce solid 3D models
◦ Used technology knows as tomography
◦ Uses
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Produce prototypes from CAD
Models are produce in color
Organic objects (human organs)
◦ Advantages
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Save a lot of money
Better idea about end product
Powders can be reused
◦ Disadvantages
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Expensive to buy
Slow producing the output
The end product can need more work at the end
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Output Devices (Cont.)
 Dot matrix printers
 Output is made up of matrix of pins
 Uses
◦ In noisy environment
◦ Print quality is not very important
 Advantages
◦ can be used in dusty environments
◦ Multipart outputs can be produced
◦ Very cheap to run and maintain
◦ Long printing jobs
 Disadvantage
◦ Very noisy
◦ More expensive to buy than an inkjet
◦ Very slow and not good quality
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Output Devices (Cont.)
 Plotters or graph plotters
◦ Very large drawings and posters
◦ No limitations about paper size
◦ Pen plotters, electronic plotters
◦ Uses
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Large dewing such as buildings or factories
Large pictures
Print on plastic coated paper
Large signs
◦ Advantages
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Huge printouts
Extremely high quality
◦ Disadvantages
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Slow
Expensive
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Output Devices (Cont.)
 Speakers
 Connected directly to the computer
 Digital signals converted into analogue using digital
analogue converter
 Uses
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Output sound
Home entertainment
Help blind people
Play downloaded sounds
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Output Devices (Cont.)
 Multimedia projector
◦ Receive signals that can be digital or analogue
◦ Images is magnified and projected into large screen
◦ Uses
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Training presentations
Advertising presentations
Home cinema
◦ Advantages
 More people can see the presentation
◦ Disadvantages
 Images sometimes be fuzzy
 Expensive
 Setting up projectors can be little different
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Control Devices
 Type of output devices
 Control devices are used
control processes in
conjunction with sensor
input devices
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Control Devices (Cont.)
 Actuators
 Transducers that convert Signals
 Sent signals form computer to the actuators such as
motors, pumps, switches etc….
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Control Devices (Cont.)
 Motors
 Turn on or off by the actuator
 Uses
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Domestic appliances such automatic washing machine,
central heading, greenhouses, etc
Control robot arms
Fans, disk drivers, DVD drivers
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Control Devices (Cont.)
 Buzzers
 Turn on or off
 Uses
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Cookers and microwave ovens to tell the operator when the
process is complete
Alarm systems
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Control Devices (Cont.)
 Lights
 Light is turned on or off
 Uses
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Security lights
Control lighting conditions
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Control Devices
(Cont.)
 Heaters
 Turn heater on or off
 Uses
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Automatic washing machines
Control of temperature
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Review Questions
A company wants to buy a printer for its office. What factors would be
important when deciding what type of printer to buy?
2.
What type of output device would be most suitable for each of the
following activities? Give at least one reason for each of your choices.
a)
General printing on a home computer, including printing letters and
other documents.
b)
Printing in a busy office.
c)
Printing customer receipts in a supermarket. The printer must
produce a second copy for the supermarket to keep on selfreplicating paper (paper that copies through where pressure has been
applied to the top copy).
1.
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Review Questions (Cont)
What type of output device would be most suitable for each of the
following activities? Give at least one reason for each of your choices.
a)
Producing a warning that a library book that has just been returned
is overdue and a fine should be paid.
b)
Showing that a disk drive is in use.
c)
Producing lists of theatre seats that are available when a customer
telephones to book a ticket.
d)
Producing high quality output for a design studio.
4. What type of input device would be most suitable for each of the
following activities? Give at least one reason for each of your choices.
a)
ATM
b)
Supermarket cashier
c)
Shopping maul map
3.
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